How to create Syntax based coloring? which language we want to use?

Are you referring to Syntax Highlighting? Any decent text processor should be able to accomodate that. If you're building a text processor from the bottom up, I could recommend doing this in Python. The speed of the prototyping effort is very high, though the code will not be threaded or anything else that'll help with efficiency - but for proof-of-concept, it is ideally suited.